Environmental Engineering

121.Noise level during normal conversation among men is about _________ decibels.

1. 10
2. 45
3. 90
4. 115

122.Noise level heard at a distance of about 100 metres from a jet engine with after burner is about _________ decibels.

1. 120
2. 140
3. 170
4. 200

123.Noise level heard inside a bus in busy city traffic or inside a sub-way train corresponds to about _________ decibels.

1. 75
2. 95
3. 120
4. 140

124.Noise level in a quiet private business office is about _________ decibels.

1. 25
2. 50
3. 70
4. 85

125.Noise level inside a jet airliner in normal flight is about _________ decibels.

1. 80
2. 100
3. 125
4. 150

126.Noise pollution level in a chemical plant is expressed in

1. Roentgen
2. Decibel
3. Hertz
4. None of these

127.Noise produced by cooling fans (employed in air cooled heat exchangers or cooling tower) is mainly caused due to the turbulence created by blade passage through air. It can be reduced by use of a slower fan

1. With greater number of blades
2. Of increased diameter
3. Both (A)&(B)
4. Neither (A) nor (B)

128.Oceans act as sinks for atmospheric gases including carbon dioxide whose concentration in the atmosphere is increased by the

1. Forestation
2. Rain
3. Green house effect
4. Vegetation

129.Oilish impurities present the effluent discharged from the electroplating industry is normally not removed by

1. Chemical coagulation
2. Floatation&skimming
3. Centrifugation
4. Ultra filtration

130.On prolonged exposure to high concentration of carbon monoxide (> 5000 ppm), man dies because

1. Of clotting of blood
2. Of jamming of respiratory tract
3. It forms carboxyhemoglobin by combining with haemoglobin of blood, thereby making it incapable of absorbing oxygen
4. It forms CO₂ by combining with oxygen present in the blood